1. Field of the Invention
The present invention relates to a device processing method including the steps of dividing a wafer into individual devices and forming a silicon nitride film on at least the side surface of each device, thereby producing a gettering effect in each device.
2. Description of the Related Art
A plurality of devices such as ICs and LSIs are formed on the front side of a silicon substrate so as to be partitioned by a plurality of crossing division lines, thus providing a wafer. The back side of the wafer is ground to reduce the thickness of the wafer to a predetermined thickness. Thereafter, the wafer is divided into the individual devices by using a dicing apparatus and the devices thus obtained are used for various electronic equipment or the like. As a method for dividing the wafer into the individual devices, there has been proposed and put to practical use a technique of focusing a laser beam inside the wafer along the division lines to form a plurality of modified layers inside the wafer along the division lines and next applying an external force to the wafer to thereby break the wafer along the division lines, thus dividing the wafer into the individual devices (see Japanese Patent No. 3408805, for example). By using this technique, the width of each division line can be reduced, so that more devices can be formed from one wafer, thereby improving the productivity.
If the modified layer is left on the side surface of each device, the die strength of each device is reduced. To cope with this problem, there has been proposed a technique of grinding the back side of the wafer after dividing the wafer into the individual devices, thereby removing the modified layers (see Japanese Patent No. 4398686, for example).